Among cancer and septic patients, there is a deregulation of common events such as inflammation. This fact limits the use of biomarkers to diagnose sepsis. Through a search in the PubMed database, we identified the clinical studies that evaluated procalcitonin as a biomarker among children with cancer and sepsis; we analyzed its characteristics, advantages and disadvantages. Most of the studies suggest that with a cut-off point between 0.5 ng/dl and 1 mg/dl, procalcitonin displays a sensitivity of 59-78%, a specificity of 76%, a predictive value of 93% and a negative predictive value of 45% to diagnose sepsis. The procalcitonin values were not modified by the use of chemotherapy or steroids. In the past few years, encouraging results have been obtained when using it as a biomarker in children with cancer, particularly with neutropenia and fever.